Recently, in terms of environmental friendliness such as space saving or energy saving types of electronic products have been increasing, which utilise liquid crystal panels or organic electroluminescent (EL) panels as display devices, representatively including liquid crystal monitors, liquid crystal televisions, feature phones, smartphones, tablet computers, electronic book readers and notebook computers. In particular, in electronic devices such as smartphones, tablet computers, electronic book readers and feature phones, the display panel, for example, a liquid crystal panel or organic electroluminescent panel, is covered by a phototransmissive cover member such as a touchpanel which allows the user to input data by touching the screen with fingers, etc., or a cover glass which covers the outer circumferential portion of the screen other than the display portion.
To bond the display panel with the cover member, an ultraviolet curable resin is applied to one of them. This one is overlapped with the other one. After the resin expands to the necessary filling area, the resin is irradiated with ultraviolet light perpendicularly to the flat surface of the cover member of the display device, thus curing the resin.
In consideration of variation in the amount of resin applied, or prevention of bubbles, it is difficult to restrict the area to be filled with the resin to only the display area (active area) which displays an image. Thus, the filling area of the resin may be expanded to the outside of the active area and range to the circumferential portion of the cover glass covered by a light-shielding layer, etc., which is hard to transmit light. In this case, the resin may not be cured or may be insufficiently cured in the portion within the filling area of the resin, that is located under the light-shielding layer which the ultraviolet light radiated perpendicularly to the flat surface of the cover member is hard to reach.